Sciarid flies

Overview

Sciarid flies (fungus gnats) are common in moist substrates; larvae can damage roots and spread pathogens.

Symptoms

• Adult gnats around media
• Root damage / poor establishment
• Algae / wet surfaces

Conditions that increase risk

• Over-wet media
• Algae / organic debris

Biological control options

• Steinernema feltiae
• Atheta coriaria
• Hypoaspis miles

IPM notes

• Dry-down strategy + hygiene + biologicals

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Further guidance

• Sciarid flies — Biocontrol Foundations

Key natural enemies

• Atheta coriaria
• Stratiolaelaps scimitus
• Steinernema feltiae

Environmental drivers

• Favoured by consistently moist substrates, high organic matter, and algae on media surfaces.
• Peaks often follow overwatering, poor drainage, or heavy propagation cycles.
• Warm conditions accelerate life cycle; hygiene strongly influences pressure.